How do I check for ‘background I/O’ as a possible cause?

If there is no change in the first step, compare the steps in order, including ‘Free up space and reboot’. If symptoms disappear immediately after certain actions or the conditions for their occurrence change, this can be an important clue in narrowing down the cause.

Disk usage is 100% in Task Manager: When do I need a professional check?

Even if you follow the above solution steps in order, if the disk 100% symptom recurs or hardware abnormal signals such as a burning smell, abnormal noise, overheating, or failure to recognize parts appear, we recommend backing up important data and performing a professional inspection.

PC FIX

Computer Troubleshooting Guide

Storage

Disk usage is 100% in Task Manager

Q: What should I check first if I see symptoms of 100% herniated disc?

First, proceed with the ‘Check physical disk usage processes in Task Manager’ step. Distinguish between background indexing, updates, and anti-virus checks or the drive's own delay. We recommend that you avoid changing multiple settings at once and check to see if your symptoms change after each step.

When troubleshooting 100% disk usage in Task Manager, it is important to rule out causes one at a time. Based on the “Disk 100%” symptom, check for background I/O and storage device response delay and proceed to the next step. Check the processes using the disk, free space, connection speed and SMART in that order.

Solving Order
We've organized the methods starting with the simplest and least expensive ones. Please check the solutions one by one, starting from the top.

Do you have these symptoms?

Disc 100%
SSD 100%
HDD 100%
Stuck due to disk usage

main causes

Background I/O
Storage device response delay
File system/driver problems

How to solve

Please check them in order from the top. If the issue is resolved, you do not need to proceed to the next step.

Check physical disk usage processes in Task Manager

Distinguish between background indexing, updates, and anti-virus checks or the drive's own delay.

Difficulty Easy time 5-10 minutes cost 0 won

1Sort by disk usage in Task Manager.
2Check response time and read/write in Resource Monitor.
3Note whether a particular process remains occupied.

confirmation point

After these steps, see if the “Disc 100%” symptom decreases or disappears. If there is no change, the possibility of background I/O is also checked in the next step.

Free up space and reboot

If your SSD is almost full, performance may suffer due to lack of cache and maintenance space.

Difficulty Easy time 10~30 minutes cost 0 won

1Check the free space on your system drive.
2Clean out temporary files, recycle bin, and unnecessary apps.
3Compare performance after reboot.

Check port/cable/link speed

Performance of an external SSD or SATA SSD is limited when connected to a slow port or cable.

Difficulty Moderate time 10-20 minutes cost 0 won

1USB devices plug directly into USB 3.x ports.
2Try replacing the SATA cable.
3For NVMe, check your motherboard documentation for the PCIe speed of your M.2 slot.

Check firmware, chipset, and storage drivers

Controller compatibility and firmware issues may cause lag or slowdowns.

Difficulty Moderate time 15-30 minutes cost 0 won

1Check for firmware updates in your SSD manufacturer tool.
2Check the motherboard/laptop chipset and storage drivers.
3Back up important data before updating.

Check SMART status and temperature

Determine whether poor performance is due to malfunctions or thermal throttling.

Difficulty Moderate time 10-20 minutes cost 0 won

1Check for SMART warnings.
2Check if NVMe temperature is excessively high during load.
3If warning and freezing are present together, data backup and replacement are given priority.

Frequently Asked Questions

We've put together a list of things we frequently check regarding this issue.

Related issues

If the symptoms do not match exactly, please check the issue below.

Storage

Problem with C drive having almost no space

If the current symptom is close to “C drive full,” first check whether there are temporary files, update files, large apps, or user files. Check the processes using the disk, free space, connection speed and SMART in that order.

View solutions →

Storage

Temporary or system files keep growing

If many temporary files are accumulating, possible causes include the Windows Update cache, application caches and dump files. Check disk activity, free space, connection speed and SMART health in that order.

View solutions →

Storage

Problem with SSD/USB/external hard drive file copy speed being too slow

If the current symptom is closer to “slow file copy,” first check whether there are many small files or USB specification/port restrictions. Check the processes using the disk, free space, connection speed and SMART in that order.

View solutions →

Storage

SSD speed is much slower than expected

If “slow SSD” occurs repeatedly, it is better to narrow it down to insufficient drive capacity and thermal throttling rather than changing several settings at once. Check the processes using the disk, free space, connection speed and SMART in that order.

View solutions →

Look for other symptoms too

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